As well known to those skilled in the art, in a toroidal variator, an input disk and an output disk are disposed to form a ring shape having a groove therebetween, and a plurality of power rollers is provided between the input disk and the output disk and couples them to each other such that power is transmitted by friction.
The toroidal variator has a relatively simple structure and is very quiet during operation thanks to reduced vibration and noise. Therefore, in the case where such a toroidal variator is used for a power train of a vehicle, the power train can quietly conduct a variable speed change operation despite having a relatively simple structure.